Louisiana
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Louisiana water profile

Nitrate in Louisiana community water systems

Louisiana runs low on public-system nitrate statewide — deep regional aquifers supply most systems — but the small cluster that does appear sits in the northeast row-crop parishes on the shallow alluvial aquifer. See the pattern and what each reporting system measured in the three years from August 9, 2023 to August 9, 2026.

Browse all 591 Louisiana systems →

Search by the utility or system name shown on a water bill. Example: City of Winnsboro. Private wells are not in this inventory.

65%
of the state’s 911 active community water systems have a current result here
591
systems with a current nitrate result
4,303,711
people served by those reporting systems
0.2%
of reporting systems at or above 5 mg/L
How to read these numbers Each system is placed into a band by its most recent reported result within a rolling three-year window. The bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Figures describe system reporting, not nitrate measured at an individual tap.

How Louisiana's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
533 systems · 3,066,482 served
Human impact likely
1.00–2.99 mg/L as N
54 systems · 1,227,434 served
Human impact clear
3.00–4.99 mg/L as N
3 systems · 8,193 served
Health-study range
5.00–9.99 mg/L as N
1 system · 1,602 served
Above the federal limit
10.00 mg/L and above
0 systems · 0 served

Each system appears in one band only, placed by its most recent reported result in the current three-year window. Counts sit beside people served so a small number of larger systems cannot hide behind a row of tiny ones. The one system reporting 5 mg/L or more did not stay there across its whole three-year range — it reached 5 only on a high sample and otherwise ran lower.

Most recent reading Dec 2025; the typical system was last tested around Mar 2025. 590 systems sampled their own water; 1 system carries a supplier’s result.

The named systems

Every reading here belongs to a utility with a name

Highest recent readings
SystemMost recent resultBandBased onPeople served
Liddieville Water System5.80 mg/LAug 2025Health-study rangeCCR summary, unverified1,602
Gilbert Water System3.50 mg/LAug 2025Human impact clearCCR summary, unverified915
West Winnsboro Water System3.50 mg/LAug 2025Human impact clearCCR summary, unverified3,078
Archibald Water System3.00 mg/LJul 2025Human impact clearCCR summary, unverified4,200
Belle Place Trailer Park Water System2.40 mg/LJun 2025Human impact likelyCCR summary, unverified330
Hebert Water System2.20 mg/LOct 2025Human impact likelyCCR summary, unverified3,048
Happy Acres Mobile Home Park2.20 mg/LJun 2025Human impact likelyCCR summary, unverified120
G & J Mobile Home Estates Water System2.20 mg/LOct 2025Human impact likelyCCR summary, unverified186
Largest systems
SystemMost recent resultBandBased onPeople served
Baton Rouge Water Company0.40 mg/LNov 2025Natural backgroundCCR summary, unverified596,844
New Orleans Carrollton Water Works1.10 mg/LJan 2025Human impact likelyCCR summary, unverified334,903
E Jefferson Ww District 11.00 mg/LJan 2025Human impact likelyCCR summary, unverified275,163
Lafayette Utilities Water System0.30 mg/LJul 2025Natural backgroundCCR summary, unverified169,389
W Jefferson Ww District 21.10 mg/LFeb 2025Human impact likelyCCR summary, unverified140,264

Each result shows its date and what it rests on, so a lone sample is never taken for a settled measurement. A single high sample is not a complete account of what a household drinks.

Where higher nitrate concentrates

A small cluster in row-crop country

Human impact is clear on drinking water served in two of Louisiana’s 64 parishes. Each is shaded by how many of its systems reported 3.00 mg/L as N or above. Shading counts systems, not severity — a parish with many small utilities can outrank one holding a single larger system that reads higher. The table beside the map splits the two bands so that difference stays visible.

LA counties shaded by number of community water systems reporting nitrate at or above 3.00 mg/L as NCounties are shaded by how many community water systems reported nitrate at or above 3.00 mg/L as N in the three years from August 9, 2023 to August 9, 2026. The same counts appear in the table below this map.Richland County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveFranklin County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or above
none1–23–56–1112–2526+Number of drinking water systems reporting ≥3.00 mg/L NO₃–N per county as of August 9, 2026

Franklin Parish leads this layer with 1 reporting system. A small cluster in row-crop country.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Franklin Parish213
Richland Parish101

Counts use each system's most recent reported result in the current three-year window. A system appears in only one of the two bands.

Find a specific Louisiana system

What the statewide pattern says

Deep aquifers protect most of the state; the shallow ones answer

Louisiana's small nitrate signal concentrates in Franklin and Richland parishes — Mississippi Alluvial Plain row-crop country where the shallow alluvial aquifer is both the irrigation supply and the local drinking source.

Louisiana's 591 reporting public systems include only a handful with groundwater nitrate above the natural-background band, and they gather in the northeast: Franklin and Richland parishes, on the Mississippi River Alluvial Aquifer. That aquifer supplies roughly 94 percent of the groundwater across the nine-parish northeast region — and all of it in Franklin, Madison and Tensas parishes — for an irrigated row-crop economy that keeps expanding (Louisiana Geological Survey, 2017).

The Mississippi embayment's water structure explains the statewide quiet: the shallow alluvial aquifer is the irrigation source, while deeper units — the middle Claiborne and the Chicot and Sparta systems — supply most public drinking water, so pumping depth alone pushes most systems' nitrate toward natural background (USGS FS 2011-3115).

The measured Louisiana baseline comes from the Chicot aquifer system, the state's most heavily pumped: a USGS–Louisiana DOTD survey of 160 shallow domestic wells found nitrate above the detection level in 32 percent of them, eight wells above 1.0 mg/L, and none above the 10 mg/L federal limit — and the higher results came from shallower wells (36–120 feet, against a 155-foot median), with septic, livestock and crop fertilizer listed among the plausible sources (USGS/DOTD Technical Report 64).

The honest gap: Louisiana has no published county-level nitrate study for the northeast parishes this page can cite — the Geological Survey's alluvial-aquifer ion analysis there is still in progress. The reading therefore stops at the setting: row-crop nitrogen on the shallow alluvial aquifer, at low measured levels — not a certified source at any individual system (Nolan and Hitt, 2006).

The general science — how nitrate moves, why some ground is vulnerable, and why the legacy lingers — is laid out with its sources on Where nitrate comes from.

Questions this page answers

What the Louisiana pattern does—and does not—say

Where does nitrate concentrate in Louisiana community water systems?

Franklin Parish leads this layer with 1 reporting system. A small cluster in row-crop country.

Why does Louisiana have so few systems on this map?

Depth. Most Louisiana public systems pump deep regional aquifers — the Chicot, Sparta and middle Claiborne — where nitrate runs at natural background. The systems that appear tap the shallow Mississippi River Alluvial Aquifer in the northeast row-crop parishes.

Should a Louisiana private well be tested for nitrate?

Yes, especially shallow wells in the alluvial and Chicot systems. The 160-well Chicot survey found occasional results above 1 mg/L in wells under about 120 feet deep, with septic, livestock and fertilizer among the listed sources — and shallow private wells in Franklin and Richland parishes share the aquifer with the systems on this map.

Does a high public-system result mean a nearby private well is high?

No. It is a local sentinel, not a well-specific result. It shows that nitrogen and a transport pathway have reached groundwater in the area; a certified-lab test is still the only way to know a specific private well.

Sources and provenance

What this page rests on

  1. NitrateSmart inventory: 591 Louisiana community water systems with a current nitrate result in the three years from August 9, 2023 to August 9, 2026. Figures count people served by reporting systems, not measured tap exposure.
  2. Nolan BT, Hitt KJ (2006). Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States. Environmental Science & Technology 40(24):7834–7840.
  3. Dubrovsky NM, and others (2010). Nutrients in the Nation's Streams and Groundwater, 1992–2004. USGS Circular 1350.
  4. Louisiana Geological Survey (2017). Mississippi River Alluvial Aquifer ion study, progress report. LGS Newsletter — alluvial aquifer supplies ~94% of groundwater in the nine-parish northeast region; 100% in Franklin, Madison and Tensas parishes.
  5. USGS (2011). Groundwater Availability of the Mississippi Embayment. Fact Sheet 2011-3115 — shallow alluvial aquifer as irrigation source; deeper Claiborne units as drinking-water supply.
  6. USGS / Louisiana DOTD. Water quality of the Chicot aquifer system, southwestern Louisiana. Technical Report 64 — 160 domestic wells, 1994–96: nitrate detected in 32%, eight wells >1.0 mg/L, none >10 mg/L; shallow wells most susceptible.